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For review only - Simulation of complex glazing products; from
optical data measurements to model based predictive controls.
Christian Kohler1
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ABSTRACT
Complex glazing systems such as venetian blinds, fritted glass and woven
shades require more detailed optical and thermal input data for their components
than specular non light-redirecting glazing systems. Various methods for
measuring these data sets are described in this paper. These data sets are used
in multiple simulation tools to model the thermal and optical properties of
complex glazing systems. The output from these tools can be used to generate
simplified rating values or as an input to other simulation tools such as whole
building annual energy programs, or lighting analysis tools. I also describe some
of the challenges of creating a rating system for these products and which factors
affect this rating. A potential future direction of simulation and building operations
is model based predictive controls, where detailed computer models are run in
real-time, receiving data for an actual building and providing control input to
building elements such as shades.
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INTRODUCTION
Windows in buildings and homes are responsible for about 4% of the total
annual energy consumption in the US (Apte 2006). This energy consumption is
related to heating, cooling and lighting in homes, offices and other buildings.
Buildings are subject to continuously changing climatic (exterior) conditions such
as solar radiation, wind and air temperature. Requirements for the interior climate
of a building are usually static and only vary slightly throughout the year or day
(daytime/nighttime mode). Windows and the rest of the building envelope are the
separation between these two environments. A static window (a window that has
properties that do not change) cannot respond to changes in the outside
conditions. Equipment that provides heating, air conditioning and ventilation is
currently the only other variable component that can help create this stable
interior climate.
Windows with operable shading devices can help by making the window dynamic
and responsive to the environment. The energy consumption associated with
static windows can also be reduced by incorporating optically complex systems,
which for example can admit light only at certain angles, rejecting light at other
angles.
Computer simulation can be used to predict how much energy a building will use.
Various annual energy simulation tools (EnergyPlus 2011, DOE2 2000) are
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Christian Kohler, [email protected] , Building Technologies Program, Environmental Energy
Technologies Division, Lawrence Berkeley National Laboratory, Mailstop 90-3111, 1 Cyclotron
Road, Berkeley, CA 94720 USA
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